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At least 19 recordsLinked to original sources
USGS2020

Climate from the McMurdo Dry Valleys, Antarctica, 1986 – 2017: Surface air temperature trends and redefined summer season

The weather of the McMurdo Dry Valleys, Antarctica, the largest ice‐free region of the Antarctica, has been continuously monitored since 1985 with currently 14 operational meteorological stations distributed throughout the valleys. Because climate is based on a 30‐year record of weather, this is the first study to truly define the contemporary climate of the McMurdo Dry Valleys. Mean air temperature and solar radiation based on all stations were −20°C and 102 W m −2 , respectively. Depending on the site location, the mean annual air temperatures on the valleys floors ranged between −15°C and −30°C, and mean annual solar radiation varied between 72 and 122 W m −2 . Surface air temperature decreased by 0.7°C per decade from 1986 to 2006 at Lake Hoare station (longest continuous record), after which the record is highly variable with no trend. All stations with sufficiently long records showed similar trend shifts in 2005 ±1 year. Summer is defined as November through February, using a physically based process: up‐valley warming from the coast associated with a change in atmospheric stability.

JGR Atmospheres↗
USGS2023

National-scale assessment of total gaseous mercury isotopes across the United States

With the 2011 promulgation of the Mercury and Air Toxics Standards by the U.S. Environmental Protection Agency, and the successful negotiation by the United Nations Environment Program of the Minamata Convention, emissions of mercury (Hg) have declined in the United States. While the declines in atmospheric Hg concentrations in North America are encouraging, linking the declines to changing domestic and global source portfolios remains challenging. To address these research gaps, the U.S. Geological Survey initiated the first national-scale effort to establish a baseline of total gaseous mercury stable isotope values at 31 sites distributed across the United States. Results indicated that unique Hg sources, such as Hg evasion from an elemental Hg contaminated site or free tropospheric intrusions in high altitude sites, were distinguishable from background atmospheric values. Minor gradients were observed across the nation, with regions of heavy industrial activity demonstrating lower δ 202 Hg, but no consistent changes in other isotopes such as Δ 199 Hg and Δ 200 Hg were observed. Furthermore, δ 202 Hg was impacted by foliar uptake and senescence but trends varied between forested regions in the northeastern and midwestern United States. These data demonstrate regional emission sources and other environmental variables can impact total gaseous Hg (TGM) isotope values, highlighting the need to characterize atmospheric Hg isotopes over larger geographical areas to evaluate changes related to national and international Hg regulations.

JGR Atmospheres↗
USGS2024

Microplastic and associated black particles from road-tire wear: Implications for radiative effects across the cryosphere and in the atmosphere

The environmental effects of airborne micro- and nano-size plastic particles are poorly understood. Microscopy and chemical analyses of atmospherically deposited particles on snow surfaces at high elevation (2,865–3,690 m) in the Upper Colorado River basin (UCRB; Colorado Rocky Mountains) revealed the presence of black substances intimately associated with microplastic fibers, particles interpreted to have originated as tire matter. Identical and similar particles occur in shredded tires and road-surface samples. The substance responsible for the black color of all tires is carbon black, a graphitic light-absorbing tire additive produced by hydrocarbon combustion that homogeneously permeates the mixture of tire polymers and other additives. Such black tire matter may thus exert radiative effects closely similar to those of black carbon. The presence in snow of many organic compound types common to tires, measured by two-dimensional gas chromatography, suggests that atmospherically deposited black road-tire-wear matter is among the light-absorbing particulates that advance the onset and rate of snow melt in the UCRB. The mass of road-tire-wear particles shed from vehicles may be estimated by multiplying measured amounts of eroded tire-per-distance traveled by vehicular distances. Under a combination of measurements and assumptions about the amounts and radiative properties of atmospheric tire-wear particles, the radiative effects of these particles might add about 10%–30% to those effects from black carbon, an estimate ripe for revision. On regional and global scales, the amounts and effects of emitted and deposited tire-wear matter likely vary by factors of geographic source, transport pathway, and depositional setting.

JGR - Atmospheres↗
USGS2019

Application of a regional climate model to assess changes in the climatology of the Eastern US and Cuba associated with historic landcover change

We examine the annual, seasonal, monthly, and diurnal climate responses to the land use change (LUC) in eastern United States and Cuba during four epochs (1650, 1850, 1920, and 1992) with ensemble simulations conducted with the RegCM4 regional climate model that includes the Biosphere Atmosphere Transfer Scheme (BATS1e) surface physics package (Dickinson et al., 1993). We derived the land use (LU) data sets by harmonizing a previous reconstruction (Steyaert & Knox, 2008) with updated observations and modeled potential vegetation. The eight‐member ensembles for each epoch were driven with randomly perturbed 1990–2002 atmospheric boundary conditions derived from the National Center for Environmental Prediction global reanalysis. LUC induces statistically significant climate responses across all epochs; the largest changes occur between 1850 and 1920 with the widespread conversion of forests in the United States and forests, grassland, and woody wetlands in Cuba to agriculture. The atmospheric feedback from the aggregated grid‐cell responses attributed to physical and biophysical parameters in BATS1e alters the circulation in the lower atmosphere, thereby propagating the LUC regionally. Depending on the season and location, the altered circulation reinforces, attenuates, or has little effect on surface responses. Relative to pre‐settlement (1650), the 1992 LU produces colder mean annual air temperature (−0.09 ± 0.16 °C) and increased precipitation (0.08 ± 0.09 mm day −1 ) over the United States, warmer (0.08 °C) and wetter (0.03 mm day −1 ) conditions over Florida, and warming (0.32 °C) and drying (−0.03 mm day −1 ) over Cuba, indicating that LUC has played a varying role in climate change over the region.

Florida↗
USGS2024

Synoptic analysis and WRF-Chem model simulation of dust events in the southwestern United States

Dust transported from rangelands of the Southwestern United States (US) to mountain snowpack in the Upper Colorado River Basin during spring (March-May) forces earlier and faster snowmelt, which creates problems for water resources and agriculture. To better understand the drivers of dust events, we investigated large-scale meteorology responsible for organizing two Southwest US dust events from two different dominant geographic locations: (a) the Colorado Plateau and (b) the northern Chihuahuan Desert. High-resolution Weather Research and Forecasting coupled with Chemistry model (WRF-Chem) simulations with the Air Force Weather Agency dust emission scheme incorporating a MODIS albedo-based drag-partition was used to explore land surface-atmosphere interactions driving two dust events. We identified commonalities in their meteorological setups. The meteorological analyses revealed that Polar and Sub-tropical jet stream interaction was a common upper-level meteorological feature before each of the two dust events. When the two jet streams merged, a strong northeast-directed pressure gradient upstream and over the source areas resulted in strong near-surface winds, which lifted available dust into the atmosphere. Concurrently, a strong mid-tropospheric flow developed over the dust source areas, which transported dust to the San Juan Mountains and southern Colorado snowpack. The WRF-Chem simulations reproduced both dust events, indicating that the simulations represented the dust sources that contributed to dust-on-snow events reasonably well. The representativeness of the simulated dust emission and transport in different geographic and meteorological conditions with our use of albedo-based drag partition provides a basis for additional dust-on-snow simulations to assess the hydrologic impact in the Southwest US.

southwestern United States↗
USGS2026

Quantifying methane emissions from a rich fen with uncrewed aircraft systems in boreal Alaska

Thawing of permafrost in northern latitudes is accelerating, potentially releasing substantial amounts of methane (CH 4 ) as forested permafrost plateaus transition into wetlands. This ecosystem shift alters the carbon exchange between the soil and atmosphere, influencing the permafrost-carbon feedback. Monitoring these changes may require measurement platforms operating across varied spatial and temporal scales. Recent advancements in small uncrewed aircraft systems (sUAS) enable high resolution CH 4 flux quantification in remote, complex terrains; however, comparisons with established methods such as eddy covariance flux towers remain limited. We used a hexacopter sUAS to quantify CH 4 emissions from the Alaska Peatland Experiment, a wetland within the Bonanza Creek Experimental Forest. Using an ensemble of methods to define the background CH 4 concentration, along with near surface emissions from soil chambers, helped constrain our flux estimates. The sUAS method yielded an average flux of 0.0077 ± 0.0019 mol s −1 CH 4 , within a factor of two concurrent tower-derived total source flux estimates (0.0036 ± 0.00042 mol s −1 CH 4 ). To assess spatial drivers of observed fluxes, we conducted a 2D footprint analysis and overlaid the results with high-resolution hyperspectral land cover classification, quantifying vegetative contributions within each footprint. This revealed higher fen representation in sUAS measurements (73.8%) than in tower footprints (58.8%), and lower tussock meadow representation (15.6% and 30.3%, respectively). These differences were consistent with known variation in vegetation-specific CH 4 emissions. Our results highlight that combining footprint modeling with land cover characterization can enhance interpretations of CH 4 fluxes and guide cross-platform comparisons.

JGR Atmospheres↗
USGS2025

Light absorbing particles deposited to snow cover across the Upper Colorado River Basin, Colorado Rocky Mountains, 2013-16: Interannual variations from multiple natural and anthropogenic sources

Atmospheric particulate matter (PM) as light-absorbing particles (LAPs) deposited to snow cover can result in early onset and rapid snow melting, challenging management of downstream water resources. We identified LAPs in 38 snow samples (water years 2013–2016) from the mountainous Upper Colorado River basin by comparing among laboratory-measured spectral reflectance, chemical, physical, and magnetic properties. Dust sample reflectance, averaged over the wavelength range of 0.35–2.50 μm, varied by a factor of 1.9 (range, 0.2300–0.4444) and was suppressed mainly by three components: (a) carbonaceous matter measured as total organic carbon (1.6–22.5 wt. %) including inferred black carbon, natural organic matter, and carbon-based synthetic, black road-tire-wear particles, (b) dark rock and mineral particles, indicated by amounts of magnetite (0.11–0.37 wt. %) as their proxy, and (c) ferric oxide minerals identified by reflectance spectroscopy and magnetic properties. Fundamental compositional differences were associated with different iron oxide groups defined by dominant hematite, goethite, or magnetite. These differences in iron oxide mineralogy are attributed to temporally varying source-area contributions implying strong interannual changes in regional source behavior, dust-storm frequency, and (or) transport tracks. Observations of dust-storm activity in the western U.S. and particle-size averages for all samples (median, 25 μm) indicated that regional dust from deserts dominated mineral-dust masses. Fugitive contaminants, nevertheless, contributed important amounts of LAPs from many types of anthropogenic sources.

Colorado↗
USGS2024

The role of the Great Plains low‐level jet in moisture transport, streamflow, and flooding in the Missouri River Basin

The Missouri River Basin, one of the primary agricultural regions in North America, is prone to large hydroclimatic variability and extreme events. The Great Plains low‐level jet (GPLLJ) is one of the major sources of moisture transport into this region, and concerns over moisture extremes already seen in the interior U.S. have been linked to changes in GPLLJ. However, the relationship between GPLLJ and precipitation in this region remains uncertain, with studies showing conflicting results that may be related to distinct types of jet events. Here, we use daily GPLLJ data to study connections between different types of jet events and precipitation, integrated water vapor transport, and synoptic conditions to better understand GPLLJ‐streamflow linkages. We assess GPLLJ conditions during historical flood events and potential future changes using CMIP6 projections. We find: (a) in May–September, GPLLJ is associated with 29%–46% of monthly precipitation and with increased precipitation intensity; (b) GPLLJ has a consistently positive impact on Missouri River streamflow over the warm season; (c) coupled jets have a larger impact on moisture transport than uncoupled jets, but streamflow impact is reduced, likely due to seasonal timing; (d) unusual jet conditions preceded historical warm‐season flood events; and (e) future projections indicate relatively small changes in GPLLJ meridional wind velocities along with large increases in moisture transport driven by humidity increases. Although future streamflow will be partially dependent on snowmelt from the upper basin, the projected intensification of warm‐season moisture transport to the Missouri River suggests possible increases in future flood risk.

Missouri River Basin↗
USGS2023

Submersed macrophyte density regulates aquatic greenhouse gas emissions

Shallow freshwater ecosystems emit large amounts of greenhouse gases (GHGs), such as carbon dioxide (CO 2 ) and methane (CH 4 ), yet emissions are highly variable. The role that aquatic macrophytes play in regulating aquatic GHG emissions is uncertain despite their ability to dominate shallow waterbodies. Here, we studied the effects of submersed macrophyte ( Ceratophyllum demersum ) density on CO 2 and CH 4 concentrations and fluxes. We conducted a 61-days experiment using mesocosms containing one of the following C . demersum density treatments: 0, 10, 20, or 30 individual shoots ( n = 3). We found that high density C . demersum had the highest CO 2 and CH 4 surface water concentrations and emissions while there was no significant difference in CH 4 in the low and medium densities and no plant control. The high density treatment lost biomass over the course of the experiment, indicating die-off and additions of organic matter to the sediment. High organic matter loading and low dissolved oxygen likely stimulated GHG production in the high density treatment. Our results emphasize that submersed macrophyte density and periods of growth and dieback are important in regulating GHG emissions, which may help explain why shallow waterbodies are high yet variable sources of GHGs to the atmosphere.

JGR Biogeosciences↗
USGS2020

Challenges in quantifying air-water carbon dioxide flux using estuarine water quality data: Case study for Chesapeake Bay

Estuaries play an uncertain but potentially important role in the global carbon cycle via CO 2 outgassing. The uncertainty mainly stems from the paucity of studies that document the full spatial and temporal variability of estuarine surface water partial pressure of carbon dioxide ( p CO 2 ). Here, we explore the potential of utilizing the abundance of pH data from historical water quality monitoring programs to fill the data void via a case study of the mainstem Chesapeake Bay (eastern United States). We calculate p CO 2 and the air-water CO 2 flux at monthly resolution from 1998 to 2018 from tidal fresh to polyhaline waters, paying special attention to the error estimation. The biggest error is due to the pH measurement error, and errors due to the gas transfer velocity, temporal sampling, the alkalinity mixing model, and the organic alkalinity estimation are 72%, 27%, 15%, and 5%, respectively, of the error due to pH. Seasonal, interannual, and spatial variability in the air-water flux and surface p CO 2 is high, and a correlation analysis with oxygen reveals that this variability is driven largely by biological processes. Averaged over 1998–2018, the mainstem bay is a weak net source of CO 2 to the atmosphere of 1.2 (1.1, 1.4) mol m −2 yr −1 (best estimate and 95% confidence interval). Our findings suggest that the abundance of historical pH measurements in estuaries around the globe should be mined in order to constrain the large spatial and temporal variability of the CO 2 exchange between estuaries and the atmosphere.

Maryland, Virginia↗
USGS2023

Comparison of ventifact orientations and recent wind direction indicators on the floor of Jezero crater, Mars

Wind-abraded rocks and aeolian bedforms have been observed at the Mars 2020 Perseverance landing site, providing evidence for recent and older wind directions. This study reports orientations of aeolian features measured in Perseverance images to infer formative wind directions. It compares these measurements with orbital observations, climate model predictions, and wind data acquired by the Mars Environmental Dynamics Analyzer. Three-dimensional orientations of flute textures on rocks, regolith wind tails extending from behind obstacles, and other aeolian features were measured using Digital Terrain Models (DTMs) derived from Mastcam-Z and navigation camera (Navcam) stereo images. Orientations of rock flutes measured in images acquired through Sol (martian day) 400 yielded a mean azimuth of 94° ± 7° (wind from the west). However, similar measurements of regolith wind tails indicate that recent sand-driving winds have been blowing from the east-southeast, nearly the opposite direction (mean azimuth = 285° ± 15°). Atmospheric modeling generally predicts net annual sand transport from the east-southeast at present, consistent with Perseverance regolith wind tail and orbital observations. The orientation of ventifact flutes thus suggests that they were formed under a different climate regime. Differences in orientations of recent and paleo-wind indicators have been noted at other Mars landing sites and may result from major orbital/axial changes that can cause significant changes in atmospheric circulation. Orientation differences between modern and older wind direction indicators at Jezero are useful clues to the climate history of the region.

JGR Planets↗
USGS2025

Nitrate loads and concentrations from forested watersheds and implications for Long Island Sound

Reduction in point sources of nitrogen has led to improvement in water quality of the Long Island Sound (LIS) since 2000, but changes in nonpoint sources are less clear. A significant yet poorly quantified nonpoint nitrogen source is the forested landscape. Because a large proportion of the LIS basin is forested, even small areal inputs from the forested landscape have a large cumulative effect on nitrogen loading to LIS. Atmospheric nitrogen deposition, the primary source of nitrogen to forested landscapes in LIS basin, has been declining for several decades. However, nitrogen export in streams does not necessarily mirror nitrogen deposition. To assess forest nitrogen export to LIS, we estimated annual average concentrations and fluxes of nitrate in 17 forested watersheds in and near the LIS basin. Average flow-normalized nitrate-nitrogen concentrations ranged from less than 0.05–0.43 mg per liter among all sites; annual flow-normalized yields ranged from 0.45 to 4.3 kg per hectare. Flow-normalized annual average concentrations and yields of nitrate between water years 1991–2021 did not monotonically increase or decrease at most watersheds. Where determined, the other major N species generally had comparable magnitude and trends. Based on the watersheds analyzed in this study, forested areas are not responding uniformly to the continued decline of atmospheric nitrogen deposition. The variability among sites may indicate that local-scale factors exert substantial influence over the magnitude and trends in nitrogen exports. One watershed that had increasing development showed an increasing trend in nitrate, but not in dissolved organic nitrogen.

Connecticut, Massachusetts, New Hampshire, New Yor↗
USGS2026

Global primary and secondary microseism multi-decade geographic variation, secular intensification, and period lengthening

Earth's long-period background seismic wavefield is dominated by two distinct processes that couple ocean wave energy to a global microseism wavefield. We assess global microseism intensity in the secondary (4–10 s) and primary (14–20 s) bands, and across eight 2 s-wide period bands between 4 and 20 s. Robustly estimated primary and secondary secular amplitude trends are estimated at 73 globally distributed seismic station sites with continuous recording spanning at least 20 years, from as early as the late 1980s through October 2025. These trends are positive at 3⁢𝜎 significance for 61 (84%) and 46 (63%) stations with global average rates for vertical-component acceleration of 0.17 ± 0.04 and 0.11 ± 0.05%/yr, for the primary and secondary bands, respectively, with corresponding rates of energy increase of 0.27 ± 0.08 and 0.15 ± 0.09%/yr. Secular intensification is also observed within all 2 s period bands between 4 and 20 s. Amplitude histories for the longest primary microseism periods (18–20 s) correlate to near-antipodal distances, reflecting long-range teleconnections attributed to large-fetch storm systems, long-range swell and Rayleigh wave propagation, and geographically correlated El Niño Southern Oscillation and other geographically extensive atmospheric influences on storms and waves. The lower average rates of intensification for the secondary microseism suggest that crossing wave systems in remote regions are either under-observed or are intensifying more slowly than the primary microseism, possibly due to increasing swell unidirectionality. Secular intensification is greatest at the longest primary microseism periods. This is consistent with a broadening of the global ocean wave spectrum by approximately 0.01%/yr which may reflect an increasing occurrence of large storm systems.

JGR Solid Earth↗
USGS2018

Infrasound signal detection and back azimuth estimation using ground-coupled airwaves on a seismo-acoustic sensor pair

We present a new infrasonic signal detection and back azimuth determination technique that requires just one microphone and one three-component seismometer. Ground-coupled airwaves (GCAs) occur when an incident atmospheric acoustic wave impinges on the ground surface and is partially transmitted as a seismic wave. GCAs are commonly detected hundreds of kilometers away on seismic networks and are observed to have retrograde particle motion. Horizontally propagating acoustic waves and GCAs have previously been observed on collocated infrasound and seismic sensor pairs as coherent with a 90° phase difference. If the sensors are spatially separated, an additional propagation-induced phase shift is present. The additional phase shift depends on the direction from which the acoustic wave arrives, as each back azimuth has a different apparent distance between the sensors. We use the additional phase shift, the coherence, and the characteristic particle motion on the three-component seismometer to determine GCA arrivals and their unique back azimuth. We test this technique with synthetic seismo-acoustic data generated by a coupled Earth-atmosphere 3-D finite difference code, as well as three seismo-acoustic data sets from Mount St. Helens, Mount Cleveland, and Mount Pagan volcanoes. Results from our technique compare favorably with traditional infrasound array processing and provide robust GCA detection and back azimuth determination. Assuming adequate station spacing and sampling, our technique provides a new and robust method to detect infrasonic signals and determine their back azimuth, and may be of practical benefit where resources are limited and large sensor networks or arrays are not feasible.

JGR Solid Earth↗
USGS2022

Sedimentary organics in Glen Torridon, Gale Crater, Mars: Results from the SAM instrument suite and supporting laboratory analyses

The Sample Analysis at Mars (SAM) suite instrument on board NASA's Curiosity rover has characterized the inorganic and organic chemical composition of seven samples from the Glen Torridon (GT) clay-bearing unit. A variety of organic molecules were detected with SAM using pyrolysis (up to ∼850°C) and wet chemistry experiments coupled with evolved gas analysis (EGA) and gas chromatography-mass spectrometry. SAM EGA and GCMS analyses revealed a greater diversity and abundance of sulfur-bearing aliphatic and aromatic organic compounds in the sediments of this Gale crater unit than earlier in the mission. We also report the detection of nitrogen-containing, oxygen-containing, and chlorine-containing molecules, as well as polycyclic aromatic hydrocarbons found in GT, although the sources of some of these organics may be related to the presence of chemical reagents in the SAM instrument background. However, sulfur-bearing organics released at high temperature (≥600°C) are likely derived from Martian sources (e.g., igneous, hydrothermal, atmospheric, or biological) or exogenous sources and consistent with the presence of recalcitrant organic materials in the sample. The SAM measurements of the GT clay-bearing unit expand the inventory of organic matter present in Gale crater and is also consistent with the hypothesis that clay minerals played an important role in the preservation of ancient refractory organic matter on Mars. These findings deepen our understanding of the past habitability and biological potential of Gale crater.

JGR Planets↗
USGS2026

Mercury cycling across a U.S. semi-arid mountain ecosystem elevation gradient

Mountains comprise ∼30% of the Earth's surface, but mercury (Hg) cycling in these regions remains understudied, particularly in the semi-arid western U.S. where strong climatic and ecological gradients in mountainous landscapes influence Hg deposition, retention, and bioaccumulation. In this study, we quantified growing season inputs, storage, and bioaccumulation of Hg along a ∼2,000 m elevation gradient in the Colorado Rocky Mountains, spanning the plains to the alpine. We measured Hg in atmospheric deposition, vegetation, soil, and 12-day-old chickadees. Accounting for percent canopy cover, open precipitation was the largest component of atmospheric deposition at all elevations, followed by throughfall and litterfall fluxes. Atmospheric Hg fluxes peaked at mid-elevations, likely due to cloud-cap dynamics and denser canopy cover. Total gaseous Hg and precipitation fluxes were highest at low elevations, likely reflecting local emissions and meteorological pooling. Surface soil Hg storage was more strongly predicted by organic matter content ( R 2 = 0.49; p < 0.01) and water retention ( R 2 = 0.45; p < 0.01) than by elevation ( R 2 = 0.21; p < 0.05). Alpine soils (66.3 ± 25.3 ng g −1 ) had significantly higher total Hg concentrations than lower elevations (<41.0 ± 12.7 ng g −1 ; p < 0.01), likely reflecting slower organic matter turnover. Soils on north-facing slopes also retained significantly higher pools of Hg in surface soils compared with south- and east-facing slopes. Vegetation Hg pools were greatest in the alpine region, likely due to long-lived plant species. Methylmercury (MeHg) concentrations in chickadee feathers peaked at mid-elevations (205 ± 155 ng g −1 ), corresponding to higher ecosystem Hg inputs via throughfall. Our results show that deposition, canopy cover, and meteorological conditions—not elevation alone—predict Hg retention and bioaccumulation.

Colorado↗
USGS2022

Modeling of barrier breaching during Hurricanes Sandy and Matthew

Physical processes driving barrier island change during storms are important to understand to mitigate coastal hazards and to evaluate conceptual models for barrier evolution. Spatial variations in barrier island topography, landcover characteristics, and nearshore and back-barrier hydrodynamics can yield complex morphological change that requires models of increasing resolution and physical complexity to predict. Using the Coupled Ocean-Atmosphere-Wave-Sediment Transport (COAWST) modeling system, we investigated two barrier island breaches that occurred on Fire Island, NY during Hurricane Sandy (2012) and at Matanzas, FL during Hurricane Matthew (2016). The model employed a recently implemented infragravity (IG) wave driver to represent the important effects of IG waves on nearshore water levels and sediment transport. The model simulated breaching and other changes with good skill at both locations, resolving differences in the processes and evolution. The breach simulated at Fire Island was 250 m west of the observed breach, whereas the breach simulated at Matanzas was within 100 m of the observed breach. Implementation of the vegetation module of COAWST to allow three-dimensional drag over dune vegetation at Fire Island improved model skill by decreasing flows across the back-barrier, as opposed to varying bottom roughness that did not positively alter model response. Analysis of breach processes at Matanzas indicated that both far-field and local hydrodynamics influenced breach creation and evolution, including remotely generated waves and surge, but also surge propagation through back-barrier waterways. This work underscores the importance of resolving the complexity of nearshore and back-barrier systems when predicting barrier island change during extreme events.

Florida, New York↗
USGS2026

Modeling the seasonality of wind-driven hydrocarbon waves in Titan’s polar lakes

Titan, the only body in the solar system aside from Earth with standing liquids on its surface, has polar hydrocarbon lakes and seas. As Titan’s atmosphere generates light winds, there should be waves on the surface of these lakes and seas, yet, direct wave observations are scant. We introduce and use PlanetWaves , an open source 4D spectral wave model, to study Titan’s waves and create seasonal maps of wave shape and propagation on Ontario Lacus and Ligeia Mare. Titan’s modeled waves grow up to 30 times larger than terrestrial waves for the same wind speed, are seasonally present and are largest in the spring and summer when winds are strongest. Average daily winds almost never exceed the wave generation threshold of 0.5–0.7 m/s. Average storm winds (∼1.5 m/s) generate waves 15–48 cm in height with a period ranging 6–10.5 s while maximum storm winds (∼4 m/s) generate waves 2.7–3.2 m in height with a period up to 32 s. Titan’s waves become fetch-independent at ∼40 km for average storm winds occurring ∼1% of a Titan year and ∼100 kilometers for maximum storm winds occurring 2-3 times per Titan decade. On Ontario Lacus, storm winds blow nearly parallel to the eastern shore, potentially driving wave modification of the smooth eastern shoreline. On Ligeia Mare, waves rarely propagate toward a hypothesized wave modified shoreline suggesting that another process, such as tectonics, may contribute to a straight shoreline morphology.

JGR Planets↗